A GREAT TEACHING MOMENT: a magnitude 6.4 earthquake in Kaktovik, Alaska on August 12, 2018. The image presents three #RasperryShake seismograms observing wave propagation across the United States. Help support our #STEMoutreach program HERE!

A large #earthquake shaked #Kaktovik, #Alaska at 14:58hrs UTC (or 09:58 am CST). The #focaldepth was 9.9kms and the #epicenter is ~48 polar degrees away from Spring, TX. The #seismograms below present the #groundmotion recorded in Spring, TX from the M6.1 event. The #figure shows a #comparison of seismograms recorded on two different #seismicinstruments at the same location – observations of differing #technologies and their associated #instrumentation sensitivities.

Top Image: Recording from the #EQ1 #EducationalSeismograph with a 10Hz filter applied.

Bottom Image: Recording from a #RaspberryShake with a bandwidth filter 0.1 to 1.2 Hz.

Recording global #teleseismicwaves, particularly large #magnitude earthquakes, is exciting, but the quake itself has the potential for damages and a very dangerous event. As #geophysicists, we seek to further our understanding of the Earth’s #geology below the #crust. These large quakes give us this research opportunity, The #seismogram below presents the #groundmotion recorded in Spring, TX from the 08/09/2018 05:25hrs UTC magnitude M6.9 powerful #Indonesianearthquake. An interpretation of the #wavephases is also provided. The seismogram was recorded on an #EQ1 #EducationalSeismograph.

TXESP had the honor of hosting the #scienceactivity at the #Willis Community Breakfast on 06/27/2018. Watching the site of giving and #service reminded us that our mission to share #scientificknowledge with the public is a great gift to give. Photographs demonstrate shake boards which facilitate learning concepts in: #geology, #geophysics, and #geohazard #engineering.

#TeachingMoment 2: This week, we have observed a very unique #seismic phenomenon through our #TX/#MA research collaboration. While #Texas is close to #tectonicplatesboundaries, and #Massachusetts is located within a “stable” plate interior, the #teleseismicwaves may arrive at our two stations at different times! When global earthquakes occur far enough away (>100 pol deg) from TX/MA, we can observe a #timedelay on the #seismographs (see below).

The three examples shown demonstrate how these specific earthquakes arrived ~12 to 13 minutes earlierin #Boston than in #Texas !! This is an effect of #wavepropagation, or how a seismic wave travels through the Earth. Why do you think the seismic waves arrived ~12 to 13 minutes later in Texas? The time difference is due to the type of geology between our two stations, how fast waves move through different types of #rocks, and overall distance (kms) between monitoring stations.

#TeachingMoment: On 09 August 2018 at 19:21hrs UTC, a moderately-sized M5.6 #earthquake occurred. If we compare two #seismographs, one located in Spring, TX and the other located in Brookline, MA, we observe a very common phenomenon – the #seismicevent is detected in #Texas, close to #tectonicplatesboundaries; but, the same event is notdetected in #Massachusetts, located within a “stable” plate interior.

On 07 August 2018, two #earthquakes were recorded by Station #E1TX. The #epicenters of both quakes are shown in the #maps below. The first event, in the #GreenlandSea was at 13:57hrs UTC, a strong M5.8 and a shallow #focaldepth of 10 kms. The second event, 2 hours later, occurred in #Columbia at 15:53hrs UTC, M5.4 and a deep focal depth of 148 kms. It is always fascinating that we can detect #teleseismicwaves traveling across the globe! The Columbian #seismogram is a nice recording of several seismic #wavephases.

Shown below: A map of the epicenters (highlighted in blue) of the two earthquakes on 08/07/2018.

On 04 August 2018, two similar #earthquakes shook #Guatemala. The #epicenters of both quakes were proximal to each other (see in map below). The first event was at 05:46hrs UTC, M4.9 and a depth of 37.7 kms. The second event, 5 hours later, occurred at 10:27hrs UTC, M5.1 and a depth of 35 kms.

Today, 09 August 2018, the largest of three recent Guatemalan earthquakes occurred at 19:21hrs UTC with a magnitude M5.6 and a focal depth of 30.2kms. If you look closely, the three #seismograms look very similar suggesting the #seismicwaves traveled similar paths towards Station #E1TX, operated by #TXESP.

Shown below: A map of the epicenters (highlighted in blue) of the Guatemalan earthquakes on 08/04/2018 and 08/09/2018.

#Missouri residents, were you awoken this morning by a light #shake or rattling noise? Today at 09:56hrs UTC (04:56 CST) a small #magnitude M2.6 #earthquake occurred near #WestPlains. We wouldn’t expect you to feel this earthquake, but it’s possible it may have made your knees wobble – let us know!

Shown below: A map of the #epicenter (highlighted in blue) of the West Plains, Missouri earthquake on 08/03/2018.